// ptr_ops.c -- pointer operations
#include <stdio.h>
int main(void)
{
	int urn[5] = { 100, 200, 300, 400, 500 };
	int * ptr1, *ptr2, *ptr3;

	ptr1 = urn;			// assign an address to a pointer
	ptr2 = &urn[2];		// ditto
						// dereference a pointer and take
						// the address of a pointer
	printf("pointer value, deferenced pointer, pointer address:\n");
	printf("ptr1 = %p, *ptr1 = %d, &ptr1 = %p\n", ptr1, *ptr1, &ptr1);

	// pointer addition
	ptr3 = ptr1 + 4;
	printf("\nadding an int to a pointer:\n");
	printf("ptr1 + 4 = %p, *(ptr + 4) = %d\n", ptr1 + 4, *(ptr1 + 4));
	ptr1++;				// increment a pointer
	printf("\nvalues after ptr1++:\n");
	printf("ptr1 = %p, *ptr1 = %d, &ptr1 = %p\n", ptr1, *ptr1, &ptr1);
	ptr2--;				// decrement a pointer
	printf("\nvalues after --ptr2:\n");
	printf("ptr2 = %p, *ptr2 = %d, &ptr2 = %p\n", ptr2, *ptr2, &ptr2);
	--ptr1;				// restore to original value
	++ptr2;				// restore to original value
	printf("\nPointers reset to original values:\n");
	printf("ptr1 = %p, ptr2 = %p\n", ptr1, ptr2);
						// subtract one pointer from another
	printf("\nsubtracting one pointer from another:\n");
	printf("ptr2 = %p, ptr1 = %p, ptr2 - ptr1 = %td\n", ptr2, ptr1, ptr2 - ptr1);
						// subtract an integer from a pointer
	printf("\nsubtracting an int from a pointer:\n");
	printf("ptr3 = %p, ptr3 - 2 = %p\n", ptr3, ptr3 - 2);

	return 0;

}